Washington — In his address to Congress on Thursday, Pope Francis never mentioned the politically charged words “climate change” or “abortion.” He never asked America to fix its immigration system or reduce carbon emissions.

He didn’t have to. It was all right there at a moral level that flew above the political fray – and at the same time dived directly into it. That was obvious from the response of lawmakers, as Democrats applauded and jumped to their feet during the environmental section while Republicans got a standing ovation rolling during the section on family. Many lawmakers’ tweets, too, reflected their political orientation.

As James Weiss, a papal historian at Boston College puts it, “the spiritual is always the political in the Catholic Church.” Moral imperatives have to be acted on, and that, by nature, makes them political. “Every moral position has a political implication. It’s naive to think otherwise.”

The pope’s gently delivered speech – the first papal address to Congress – did explicitly call for two actions: to abolish the death penalty and to stop the arms trade. But the speech was framed as “a dialogue” with Congress and the American people, carried out using the examples of four historic US figures, including Abraham Lincoln and Martin Luther King Jr.

The word “dialogue” infused the speech, Professor Weiss notes. That emphasizes the papacy and bishops as “conversation partners, not cultural warriors,” he says. Francis “is acknowledging that people of goodwill differ seriously, and he’s trying to transcend the deadlocks in cultural, religious, and political life.”

Holding up America’s own history and values to those listening to the speech was a brilliant device, observers say. “What a great address – building around those four figures. Never a hint of lecture or scolding,” writes Richard Garnett in an e-mail. Professor Garnett teaches law at the University of Notre Dame in Notre Dame, Ind., and specializes in religion and the public square.

Lincoln, who resolutely led the country during the stark challenges of the Civil War, became the vehicle to address global conflict and political division, as the pope warned against “every type of fundamentalism” and “every form of polarization” that divides people into “simplistic” camps.

“We must move forward together, as one, in a renewed spirit of fraternity and solidarity,” Francis said, standing before a brightly lit chamber that included four members of the US Supreme Court as well as President Obama’s Cabinet. It was a section that drew repeated bipartisan applause.

The pope then held up the “dream” of civil rights leader King and what it meant to African-Americans – to which the entire chamber stood and clapped. But when he segued into comments that extended that dream to refugees and immigrants who “travel north in search of a better life,” it was mostly Democrats who showed their praise.

“We must not be taken aback by their numbers,” Francis said, referring to both refugees and immigrants, “but rather view them as persons, seeing their faces and listening to their stories, trying to respond as best we can to their situation” and not “discard whatever proves troublesome.”

The pope invoked the Golden Rule to “do unto others as you would have them do unto you.” Then moments later he applied that same rule to “protect and defend human life at every stage of its development,” to which Republicans led the chamber in a standing ovation. Even a whistle of support rang out.

Two lesser-known 20th-century figures were next – Dorothy Day, a Catholic journalist, socialist, and social welfare activist whom the pope used to ask for vigilance in the fight against poverty and hunger; and Thomas Merton, a Catholic writer whom the pope described as “a thinker” and “a man of dialogue and promoter of peace.”

It was from Merton that Francis jumped into what seemed to be – but was not directly stated – praise for President Obama’s nuclear deal with Iran and rapprochement with Cuba, in which the pope himself played a role.

“I would like to recognize the efforts made in recent months to help overcome historic differences linked to painful episodes of the past,” he said. When countries at odds resume dialogue – “a dialogue which may have been interrupted for the most legitimate of reasons” – new opportunities open, he said. “A good political leader is one who, with the interests of all in mind, seizes the moment in a spirit of openness and pragmatism.”

Democrats applauded; Republicans sat mostly silent.

The reaction was similar when the pope referred to his May encyclical, "Laudato Si," which warned against climate change. But he didn't use those words, instead calling for a “courageous and responsible effort to redirect our steps” and avert “the most serious effects of the environmental deterioration caused by human activity.” America and Congress have an important role to play, he said – but not mentioning what, exactly, that role should be.

“It was probably prudent for him not to go into great detail, because after all he’s a spiritual leader and not a political leader,” says John Pitney, a congressional expert at Claremont McKenna College in Claremont, Calif. “The disadvantage of that approach is that everybody can hear what he or she wants to hear.”